Caption: Ivory. Coloured scanning electron micrograph (SEM) of a fractured elephant tusk, which is the source of ivory. In ivory and teeth, there is an inner pulp cavity surrounded by dentine (purple), which is made up of connective tissue and collagen. The dentine is then covered in a bony layer called cementum and then enamel forms the outer layer. Dentine is the main component in ivory and it is this layer that is used for carvings and inlays. Magnification: x80 when printed 10 centimetres wide.